Parts and outer layers having differing physical properties

ABSTRACT

Some examples include a computer-readable medium storing executable instructions which, when executed by a processor, are to cause the processor to receive electronic data describing a part to be manufactured in a three-dimensional additive manufacturing process; develop instructions using the electronic data for creating an outer layer on a surface of the part in the additive manufacturing process, where the outer layer having a physical property that differs from that of the surface of the part; and manufacture the part using the instructions.

BACKGROUND

Three-dimensional printed parts that have been manufactured using an additive manufacturing process may contain surface imperfections resulting from the additive manufacturing process. These surface imperfections may be removed manually during post-processing to create the final desired shape, texture, and/or color. For example, a part manufactured using certain additive manufacturing processes may have small artifacts or imperfections on the exterior. These imperfections or irregularities may be removed by chemical or mechanical means. Bead blasting is an example of a mechanical post-processing method in which the exterior surface of a manufactured part is ablated using a pressurized stream of air or other fluid containing small, abrasive particles or beads.

BRIEF DESCRIPTION OF THE DRAWINGS

Various examples will be described below referring to the following figures:

FIG. 1 is a cross-view of a three-dimensional part made in an additive manufacturing process in accordance with various examples;

FIG. 2 is a cross-view of another three-dimensional part made in an additive manufacturing process in accordance with additional examples;

FIG. 3 is a cross-view of another three-dimensional part made in an additive manufacturing process in accordance with additional examples;

FIGS. 4A-4B are flow diagrams of methods in accordance with various examples; and

FIG. 5 is a block diagram of an additive manufacturing system in accordance with various examples.

DETAILED DESCRIPTION

An additive manufacturing system begins building a three-dimensional (3D) part by receiving data comprising a 3D model of the part to be manufactured. The model may contain surface color information, for example, color information supplied by texture mapping data in the 3D model. The manufacturing system processes the 3D model data, which may include surface color information, to determine the processing parameters of the part. For example, the parameters may specify that a color layer be formed on the exterior surface of one or more portions of the part.

While processing the 3D model, the system may also determine where post-processing may occur on the surface of the part, for example, ablating the surface using bead blasting to remove surface irregularities in vertical walls. In those locations where such surface removal is anticipated, the system may add an additional thin layer having the same visible color as the underlying portion of the part. This additional outer layer may include a visually imperceptible property or mechanism to contrast the outer layer from the underlying surface. For example, the thin outer layer may be formed using an ultraviolet (UV) fluorescent color that appears to be the same color as the underlying surface under ordinary white light. However, when the 3D part is illuminated by UV light, those areas where post-processing may occur are highlighted by the contrasting fluorescent color. Likewise, the outer layer may be formed using a material with magnetic properties that are not visually perceptible, but which can be sensed using instruments.

A human operator or automated device that is sensitive to the properties of the contrasting outer layer is thus able to remove or ablate the outer layer at predetermined locations until the outer layer is no longer detectable. For example, the ablation process may be stopped when a fluorescent color is no longer observable or when magnetism is no longer detected. When the outer layer is no longer detectable, the underlying portion of the 3D part is considered complete or ready for further processing.

Prior solutions for manual bead blasting may require the user to know what the part and final finish of the part should look like and to make dynamic, real-time decisions about where and how much bead blasting is needed, which may require skill and attention by a highly trained operator. Other prior automated solutions for bead blasting may simply process all portions of a 3D printed part for a preset amount of time, which may not be ideal for all surfaces on the part.

Examples in accordance with the present disclosure include methods for manufacturing a 3D printed part with an outer layer having a non-visually perceptible physical property. Additional examples in accordance with the present disclosure include methods for post-processing a 3D printed part using the outer layer to guide the post-processing.

FIG. 1 shows a part 100 manufactured in a 3D printing additive manufacturing process. In these processes, electronic object model data describing the 3D part is supplied to the 3D printer. The object model data is processed in the 3D printer to develop instructions for manufacturing the part in an additive manufacturing process. During this processing, the 3D printer may also develop instructions for creating a thin outer layer 130. By way of example, the instructions for creating the outer layer 130 may be developed by adding a thin outer layer 130 having a thickness T₂ of about 0.25 mm. In the example of FIG. 1, the outer layer 130 has a uniform thickness T₂ and is formed around the entire exterior surface 110 of part 100. As discussed in more detail below, other examples may provide an outer layer 130 at selected portions of the exterior surface 110 and/or having a varying thickness depending on the expected benefit for post-processing at particular locations.

In one example, outer layer 130 is printed in an additive manufacturing process with the same visible color as the underlying portion of the part 100. For example, the outer layer 130 may include a selected physical property that distinguishes the outer layer 130 from the underlying portions of part 100. As discussed in more detail below, this selected physical property may be a fluorescent color that appears under UV light, a UV or near infrared (IR) color outside the normal visible spectrum, or a higher level of magnetism.

In one example, the outer layer 130 may be printed with a fluorescent color that has the same visible color as the underlying portion of the part 100 when viewed under normal white light (e.g., light having widely dispersed wavelengths predominantly in the visible spectrum of 390-700 nm). When the fluorescent color in the outer layer 130 is viewed under UV light (e.g., light having wavelengths predominantly in the UV spectrum of 10-400 nm), the color fluoresces and produces a color having a distinctly greater brightness than the non-fluorescent color of the underlying portion of the part 100. Thus, under white light, the outer layer 130 is not visibly distinct from the underlying portions of the part 100. However, under UV light, the outer layer 130 appears with a visually distinctive brightness.

Post-processing the part 100 may involve ablating the exterior using a bead blasting apparatus and the outer layer 130 to remove surface imperfections. Here, the part 100 may be bead blasted under UV light to precisely guide the desired location and depth of the ablation process. The outside surface of the part 100 is ablated until the fluorescent outer layer 130 is no longer observable under UV light. In this manner, ablating may be directed at particular locations and not leave an excess of the outer layer 130, while also not removing underlying portions of the part 100, either of which could adversely affect the appearance and dimensional accuracy of the finished part 100.

The non-visually perceptible physical property of the outer layer 130 may also be magnetism, or result from outer layer 130 including a UV or IR color. For example, when outer layer 130 is applied in the additive manufacturing process, a small amount of magnetic particles may be added to the build material. Alternatively, the magnetic property may be supplied in the fusing agent, other build components, or by other means. The outer layer 130 may thus be detected using a magnetic sensor and the ablation process more precisely guided in a manner similar to using a fluorescent color, as discussed above.

As noted, outer layer 130 may also be formed using a color that appears visually the same color as the underlying part 100, but which also includes a reflective UV or IR color component. As used herein, IR colors are those having wavelengths predominantly in the IR spectrum of 700-1,000 nm. These UV and IR colors may be detected using an image sensor. For example, most image sensors manufactured using a charge-coupled device (CCD) or a complimentary metal-oxide semiconductor (CMOS) device are able to sense colors in a range of wavelengths from 350 nm to 1,000 nm (which includes both UV and IR light).

When the outer layer 130 includes a UV or IR color, the outer layer 130 appears as the same visible color as the underlying portions of the part 100. However, when the outer layer 130 is viewed using an image sensor, the UV or IR wavelengths are detected and may be highlighted for a user. In this manner, the outer layer 130 may be detected by an operator 100 using an image sensor and the ablation process more precisely guided in a manner similar to ablation using a fluorescent color, as discussed above.

Alternatively, the non-visually perceptible physical property of the outer layer 130 may be used in automated or partially automated post-processing. For example, the part 100 may include an outer layer 130 having an IR color component. The part 100 may be mounted on a three-axis gimbal that is controlled by an automated bead blasting machine. The bead blasting machine may include an image sensor which continuously detects an image of the surface of the part 100 at the point where the stream of beads impacts the surface. The bead blasting process continues at this location on part 100 until the sensed image no longer contains IR color, whereupon the part 100 is rotated on the gimbal mount to a new location that does contain IR color. When the IR color is no longer detected by the image sensor, post-processing is complete.

FIG. 2 illustrates a part 100 that includes a color layer 120 on the exterior surface 110. The color layer 120 may be specified as part of the electronic data provided to the printer to describe the 3D model of the part, for example, a texture map. Alternatively, instructions for the color layer 120 may be developed by specifying a single color, by manual data input on the 3D printer, or by other means. In these examples, outer layer 130 is created on top of the color layer 120.

The process of developing instructions to create the outer layer 130 in the 3D printer may account for the additional thickness T₁ of any color layer 120. By way of example, thickness T₁ of color layer 120 may be 0.75 mm, in which case the outer layer 130 may be created at a distance of 0.75 mm from the surface 110 of part 100. Under these circumstances, the visible color of the outer layer 130 may match the visible color of the color layer 120. In addition, the non-visually perceptible physical property of the outer layer 130 differs from this same property of the color layer 120. For example, the fluorescent color of the outer layer 130 may differ from any fluorescence emitted by the color layer 120. Similarly, if magnetism is used as the physical property, the magnetism of the outer layer 130 may differ from the magnetism of the color layer 120.

The method of post-processing the part 100 illustrated in FIG. 2 is much the same as post-processing the part 100 as illustrated in FIG. 1. The post-processing, such as ablation, may continue while the human operator or automated apparatus senses the non-visually perceptible physical property of the outer layer 130. The post-processing may stop when the non-visually perceptible physical property is no longer detected. When the non-visually perceptible physical property is no longer detected, the color layer 120 would remain on the exterior surface 110 of part 100. With traditional post-processing that does not use an outer layer 130, there may exist a risk that post-processing would ablate through the color layer 120, revealing the underlying portions of part 100 which may have a different color. Under those circumstances, such a visible flaw may suggest rejecting part 100. Using outer layer 130 reduces the risk of exposing underlying portions of part 100 and increases the likelihood that the finished part 100 will more closely match the dimensions and color of the model supplied to the 3D printer.

FIG. 3 illustrates an alternative example of a part 100 with an outer layer 130 that is useful for guiding post-processing to remove surface imperfections or irregularities that are predictable or inherent in a particular additive manufacturing process. By way of example vertical walls may often contain small printing artifacts more so than horizontal surfaces. Certain types of additive manufacturing processes may be inherently predisposed to leaving surface artifacts or imperfections at certain known locations on the surface of a part 100 manufactured in the process. The 3D printer may use these inherent characteristics, together with the data describing the 3D model of the desired part 100, to develop instructions for creating an outer layer 130 at the known locations where surface artifacts or imperfections are likely to appear. The same process may be used to develop instructions for creating an outer layer 130 with a varying thickness. For example, the outer layer 130 may be thicker at locations where surface artifacts or imperfections are expected to be deeper, and thinner where the artifacts or imperfections are expected to be shallower.

Referring to FIG. 3, part 100 has a sloping portion P₁, a vertical portion P₂, and a horizontal portion P₃, all as specified in the electronic data supplied to the 3D printer for describing the 3D model of part 100. When the electronic data is processed to develop instructions for creating part 100 in the additive manufacturing process, the 3D printer recognizes that deeper surface artifacts are more likely to develop on vertical portion P₂, that shallower artifacts are likely to develop on sloping portion P₁, and that no artifacts are likely to develop on horizontal portion P₃. Thus, the 3D printer develops instructions to create an outer layer 130 with a greater thickness T₅ at the vertical portion P₂, a shallower thickness T₃ at the sloping portion P₁, and a very small or no thickness T₄ at the horizontal portion P₃. As with the other examples, outer layer 100 is created in the additive manufacturing process with a physical property that is not present on the underlying portions of part 100, e.g., a fluorescent color, a UV or IR color, or magnetic properties.

When the part 100 illustrated in FIG. 3 has completed the additive manufacturing process, manual or automated post-processing may occur as with the preceding examples. The physical property in outer layer 100 guides the location and amount or duration of post-processing desired to create a part 100 without surface artifacts or imperfections, while also having accurate dimensions as originally specified in the electronic data describing the 3D model.

FIGS. 1-3 depict manufactured parts, but the depictions in these figures are also illustrative of the 3D models that may be used to manufacture the parts described herein. As such, separate drawings of 3D models are not provided.

FIG. 4A is a flow diagram of a method 400 in accordance with various examples. The method 400 begins by receiving electronic data that describes a three-dimensional part to be manufactured in an additive manufacturing process (block 402). As explained, such electronic data may include, for instance, texture data. The method 400 continues by processing the electronic data to develop instructions for creating a 3D outer layer on an exterior surface of the 3D part (block 404). The outer layer has a physical property that is not shared by a portion of the part underlying the outer layer (block 404). Examples of such a physical property are provided above. The method 400 then includes manufacturing the 3D part by additive manufacturing, including using the instructions to manufacture the outer layer (block 406). The method is then complete.

FIG. 4B depicts a flow diagram of a method 450 that is a variation of method 400. The method 450 comprises receiving electronic data that describes a three-dimensional part to be manufactured in an additive manufacturing process, where the physical property is a fluorescent color which contrasts with the underlying portion of the part under ultraviolet light, an ultraviolet or infrared color, or magnetism (block 452). The physical property is not present on a portion of the part underlying the outer layer (block 452). The method 450 then includes processing the electronic data to develop instructions for creating a three-dimensional outer layer on an exterior surface of the three-dimensional part, with the outer layer having a physical property that is not shared by a portion of the part underlying the outer layer (block 454). The processing includes developing the instructions based on an expected need for post-processing selected portions of the exterior surface of the part to remove surface imperfections (block 454). The developed instructions specify manufacturing the outer layer on selected portions of the exterior surface of the part (block 454). The method 450 then includes manufacturing the three-dimensional part by additive manufacturing, including using the instructions to manufacture the outer layer (block 456). The manufacturing includes using the instructions to manufacture the outer layer on the selected portions of the exterior surface of the part (block 456). The method is then complete.

FIG. 5 depicts a block diagram of an additive manufacturing system 500. The system 500 may perform some or all of the actions described above, including the generation of 3D models that describe 3D parts and 3D outer layers adjacent to such parts, as well as the manufacture of parts consistent with such models. In some examples, the system 500 comprises a processor 502, a computer-readable medium (e.g., storage) 504, and additive manufacturing components (e.g., print beds, extruders, etc.) 512. The storage 504 may store electronic data 506, such as the electronic data described above; one or more 3D models 508, such as the 3D models described above; and executable code 510, which, when executed by the processor 502, may cause the processor 502 to perform some or all of the actions attributed herein to the processor 502 and/or, more generally, to the additive manufacturing system 500.

The examples discussed above enhance various additive manufacturing processes by facilitating simpler and more precise post-processing, whether post-processing is automated or performed manually. When manual post-processing is employed, the examples discussed above may not benefit from advanced knowledge of the final dimensions of the manufactured part, and they may not benefit from a high level of skill and attention by a highly trained operator as with prior art solutions.

The above discussion is meant to be illustrative of the principles and various examples of the present disclosure. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications. 

What is claimed is:
 1. A computer-readable medium storing executable instructions which, when executed by a processor, are to cause the processor to: receive electronic data describing a part to be manufactured in a three-dimensional additive manufacturing process; develop instructions using the electronic data for creating an outer layer on a surface of the part in the additive manufacturing process, the outer layer having a physical property that differs from that of the surface of the part; and manufacture the part using the instructions.
 2. The computer-readable medium of claim 1, wherein the physical property is magnetism, an ultraviolet color, or an infrared color.
 3. The computer-readable medium of claim 1, wherein the physical property is a fluorescent color that contrasts with the surface of the part under ultraviolet light.
 4. The computer-readable medium of claim 1, wherein the outer layer has varying thicknesses.
 5. The computer-readable medium of claim 4, wherein the varying thickness is determined based on the electronic data such that the thickness is greater in positions on the surface of the part where artifacts or imperfections are likely to occur.
 6. A computer-readable medium storing executable instructions which, when executed by a processor, are to cause the processor to: generate a model of a three-dimensional part, the model including an outer layer abutting a surface of the three-dimensional part, the outer layer and the surface sharing a common visually perceptible color and not sharing a physical property; and manufacture the three-dimensional part in accordance with the model and using additive manufacturing.
 7. The computer-readable medium of claim 6, wherein the physical property is magnetism, a fluorescent color that contrasts with the surface of the three-dimensional part under ultraviolet light, or an ultraviolet or infrared color.
 8. The computer-readable medium of claim 6, wherein the outer layer of the model has a non-uniform thickness.
 9. A method comprising: receiving electronic data that describes a three-dimensional part to be manufactured in an additive manufacturing process; processing the electronic data to develop instructions for creating a three-dimensional outer layer on an exterior surface of the three-dimensional part, the outer layer having a physical property that is not shared by a portion of the part underlying the outer layer; and manufacturing the three-dimensional part by additive manufacturing, including using the instructions to manufacture the outer layer.
 10. The method of claim 9 wherein the physical property is a fluorescent color which contrasts with the underlying portion of the part under ultraviolet light.
 11. The method of claim 9 wherein the physical property is an ultraviolet or infrared color.
 12. The method of claim 9 wherein the physical property is magnetism.
 13. The method of claim 9 wherein the processing includes developing the instructions based on an expected need for post-processing selected portions of the exterior surface of the part to remove surface imperfections.
 14. The method of claim 13 wherein the outer layer has a physical property that is not present on a portion of the part underlying the outer layer.
 15. The method of claim 13 wherein the developed instructions specify manufacturing the outer layer on selected portions of the exterior surface of the part, and the manufacturing the part includes using the instructions to manufacture the outer layer on the selected portions of the exterior surface of the part. 